If there wasn't a door in the utility area behind the kitchen on this plan, could the roofline on the front porch be adapted to the four foot utility area?
Yes, you could do a hip roof on the rear pop out. I did a shallow shed roof so as not to cut into the upper level window. Project your new roof layout onto the rear elevation to see how it looks and what, if anything, it means to the window layout.
If you are just doing the 4' deep pop out it shouldn't be a problem.